The drawing (DWG) file viewer is among the most important of AutoCAD third-party products. Ironically, the DWG viewer is popular because it allows users to do without AutoCAD. In fact, the viewer's primary function is to display AutoCAD drawings outside of AutoCAD.
Ever since Cyco International first pioneered the product category with AutoManager in 1987, viewers have become increasingly sophisticated. In addition to displaying DWG files, today's viewers display drawing files from competing CAD packages, plotter files, and files in many popular raster formats. The DWG viewers have drawing tools (euphemistically referred to as "redlining"), the ability to plot and print drawings, convert between file formats, and hook into other applications via programming links.
There are several dozen DWG viewers on the market. Most run independently of AutoCAD under DOS or Windows, a few with UNIX, some inside of AutoCAD as an ADI application, and a couple are built into ADI display drivers. Most vendors have more than one version of their DWG viewer, usually a low-cost basic version (one even has a shareware version) and several extra cost add-on modules or a more expensive "full feature" version. Unlike other product categories among AutoCAD add-ons, we were impressed with how different the viewers were from different vendors.
To help narrow down the field, we asked all known vendors for their stand alone DOS or Windows based DWG viewers. That left out those viewers that run inside of AutoCAD or a display driver, and those that are meant for network based drawing management. We received 20 DWG file viewer software packages, of which we review 14 here. Of the six we did not review, five were subsets of a more expensive product, one was a beta, and one arrived on a blank, unformatted diskette; the replacement did not arrive in time.
Naturally, not all products perform all these tasks. For this reason, you should match your requirements with each product's feature list to see which product best meets your needs.
We created separate load-and-display tests for the DOS- and Windows-based products. The benchmark was in two parts: loading the program, then loading the Airport.dwg file, a 960K'3 drawing. We compared the load times with AutoCAD Release 12 for DOS and Windows.
DOS-based viewers load and display the DWG file in an average 35 seconds, nearly six times faster than Release 12. The fastest of the group is Cyco's AutoManager, at 27 seconds.
Windows-based viewers load and display the DWG file twice as slowly as the DOS group: an average of 77 seconds. Still, they are on average four times faster than Release 12 for Windows and three times faster than AutoCAD LT. The fastest is Cyco's AutoManager for Windows.
Unlike a raster image, there are many ways to view a vector image: last-saved view, extents, named views, 3D views, viewports, and Paper or Model Space. All DWG viewers offer a subset of the possible views none display named UCS views, perspective views, rendered views, or perform hidden-line removal. Some viewers have an option to display drawings in monochrome, which is useful for technical publishing.
While some of the viewers display Generic CADD GCD files, none display AutoSketch SKD files or files from Autodesk's other software products.
We used several files to ensure that the viewers display AutoCAD entities accurately. We noted errors by two viewers. Informative Graphics' Myriad Windows did not display some entities in the PumpSol.dwg; Kamel Software's FastLook Plus displayed the variable width polyarc in Layer300.dwg with a reversed taper. If you find errors in the display, contact the vendor who may have an update.
After all, you want to see the drawing, not edit it. All DWG viewers let you toggle settings for greater accuracy or greater speed. The settings include:
All viewers provide a subset of these settings. Figure 1 shows AutoManager with a detail of the Airport drawing with speed settings turned on. We tested all DWG viewers with settings toggled for fastest load and view times.
A related issue is graphics board support. A higher resolution (such as 1024x768 pixels) lets you see more detail (greater accuracy) than a lower resolution (such as 640x480); a coprocessed graphics board (such as an 85l4/A or 83) displays the drawing faster than a frame buffer (such as the commonly used VGA). Most of the DOS-based viewers display at 640x480 pixels or higher. All the Windows-based viewers naturally use whatever display driver that your Windows system is using.
The feature I find most useful is being able to display the individual blocks, block names, and pinpoint their locations in the drawing. Some viewers display the block in a dialogue box but not its location in the drawing.
Most viewers give you full control over layers. They list the layer names and toggle the display of layers. Cyco's AutoManager even lets you change the layer color and linetype.
Other data displayed includes time of creation, AutoCAD version number, attribute information, and named views. Kamel's FastLook Plus and AutoSight's ProView were the products that provided the most information.
While most of the Windows-based viewers let you load a drawing by dragging the file name from the File Manager, Cyco also lets you drag the drawing from its Windows AutoManager into AutoCAD .
Informative Graphics' Myriad Windows and Cimmetry Systems' AutoVUE compete for the longest list of file formats. Myriad concentrates on file formats used in the engineering graphics. AutoVUE's includes file formats more familiar to desktop publishing.
All viewers with redlining also let you edit the redline entities. The editing capabilities vary widely, but all viewers allow you to erase redlines. Slick/386 DOS has the greatest capabilities, down to a user interface that looks very much like AutoCAD's (see Figure 7). Slick DOS lets you move, copy, delete, and change text, as well as snap to geometric features (object snap).
DWG viewers do not directly modify the DWG file to ensure the integrity of the original file. Thus, the redlining and notes are imported back into AutoCAD as a separate DWG or DXF file. Since you can redline a new (empty) drawing, that makes the viewers a simple DWG-compatible drawing package.
In addition to redlining, most viewers measure distances. A very few also let you measure perimeters and areas.
Some of the viewers include a programming interface that lets you control the DWG viewer from another application. This feature lets you display an AutoCAD drawing from within a database program, for example. Kamel Software includes sample code for linking FastLook Plus with Paradox, Visual Basic, Superbase, and Microsoft Access.
We tested the speed and accuracy of the DWG viewers against AutoCAD Release 12 for DOS and Windows on a 40MHz 386 with 8MB RAM, DOS 6.2, Windows for Workgroups 3.1, and 12 MB virtual RAM. The test drawings were those used to test DWG translators (CADENCE, March 1993): Layer 3OOldwg for Release 12 accuracy, Airport.dwg for speed, PumpSoLdwg; for AME: accuracy, Wrench.dwg; for Region accuracy, and Site-3D.dwg for Xref and Paper Space accuracy.
SoftSource provides its DOS DRAWING Librarian in three levels:
Junior ($125) just displays drawings; Standard ($250) adds more
file formats, translation, and printing; and Professional
($500), which is reviewed here, plus the Windows version called
DL for Windows ($99), also reviewed here.
DRAWING Librarian Standard an Professional display up to 25
drawings in tiled viewports but are limited to displaying just
DWG, DXF, SLD, BAK, HPGL and PCX files. Conversion is limited
to DXF, SLD, and HPGL formats.
DRAWING Librarian Professional has the unique ability to group
up to 25 drawings by a single project name. This feature lets
you view, copy, and delete all drawings in a single project.
Another unique ability is being able to place redline blocks
(see Figure 6).
The linking feature performs an action when you click on a part
of the drawing, such as display text, another drawing, or
execute a script file. In addition, you can create these links
with attributes defined in the drawing.
DRAWING Librarian Professional has a scripting language that
lets you create mini-programs that are executed from the menu,
with a keystroke, or by clicking a hot spot on a drawing. The
software package comes with a number of applications written in
its script language, such as comparing two drawings, converting
drawings to PostScript, and search through a DWG for a specific
text string. To access the DWG file directly, SoftSource has the
extra cost DXE, a library of API and DDE routines.
DL for Windows is clearly a subset of the DOS version (see i
figure 2). It only reads DWG and DXF files and only converts to
BMP and WMF via the clipboard. It is limited to displaying a
single drawing at a time and listing 100 block names. There is
no redlining capability. Besides being low priced, DL for
Windows' other strength is that it has DDE command names for all
menu items.
Drawing Librarian Professional takes three seconds to load
itself and another 39 seconds to load the Airport.dwg file,
about 5.3 times faster than Release 12 DOS (combined times). DL
for Windows takes five seconds to load itself but another 1:33
(min:sec) to load the Airport.dwg file, about 2.i times faster
than AutoCAD LT (combined times).
CADENCE REVIEW - JUNE 1994
THE VIEWERS
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